The present invention relates to a laminated tape adapted for imprinting of selected indicia thereupon and a method for forming and imprinting the laminated tape.
In the prior art, a number of different techniques have been described for forming various selected indicia or designs upon a film or tape. Within this prior art, indicia have, for example, been applied to tape by creasing or producing tensile stress within the tape in a pattern of narrow linear elements. Stressing the tape in this manner causes the linear features of the pattern to assume a white or lightened color relative to the normal tape color. Thus, this technique and apparatus have commonly been employed for producing labels and the like by applying numbers, letters and other designs to the tape.
Although widely popular, this prior art technique has demonstrated certain limiting characteristics. For example, because of the need for applying substantial pressure in order to produce tensile stress sufficient to result in a color change of the tape, its use is generally limited to formation of designs such as letters, numbers or the like which are formed by generally thin linear elements. The need for developing substantial tensile stress within the tape in order to proudce the desired color change makes it difficult to form designs having portions of substantial width or dimension. At the same time, tape adapted for use with the technique described above is formed from a pigmented plastic or a clear plastic joined to a colored adhesive, which plastic is lightened or changed to a white color by the application of stress. Thus, this technique is generally limited to production of a tape having a single background color with the imprinted designs in the form of letters, numbers or the like being either white or a lighter variation of the same background color.
Various other techniques have also been made available in the prior art for imprinting laminated tape or the like. For example, Cutler et al U.S. Pat. No. 3,575,755 issued Apr. 20, 1971 relates to a laminated tape including a layer of heat-shrinkable material. A selected design was applied to the tape by heating selected portions of the tape thereby causing the heat-shrinkable material to pull away and expose a separate layer of an underlying material having a contrasting color or the like, thus forming a selected design or indicia. However, with this technique, its laminated tape was relatively complex at least in part because of the requirement for the material to be heat-shrinkable. In addition, the final design depended upon the amount of shrinkage for different parts of the design so that resolution of the finished design tended to vary depending upon the tape and application of the selected design.
Kanzelberger U.S. Pat. No. 4,047,996 issued Sept. 13, 1977 related to yet another method and apparatus for imprinting plastic plates wherein pigment was transferred from a carrying film in a technique commonly referred to as a hot stamp process. Thus, the method and apparatus of this reference were more commonly classified under the term "applique" differing substantially from the tape and method of the present invention.
Perrington et al U.S. Pat. No. 4,123,309 issued Oct. 31, 1978 related to a transfer letter system wherein pigment was transferred from a carrier film by selectively softening portions of a design with radiation and allowing those portions to adhere to another strip or tape of contrasting color. Here again, it may be seen that the technique of this reference also fell within the classification of an applique.
Scher et al U.S. Pat. No. 4,092,198 issued May 30, 1978 related to a process for embossing and laminating wherein substantial pressures and temperatures were applied over long periods of time to a thermosetting plastic in order to produce a contrasting pattern having gradual color transitions. The process was relatively complex involving application of excessive pressures in the range of 800 to 1200 psi, for example, and excessive temperatures in the range of 260.degree.-310.degree. F. These conditions were necessary since the invention further contemplating formation of the design in a coating formed from a thermosetting plastic such as a melamine resin, the excessive pressures and temperatures being necessary to produce limited lateral movement resulting in a pattern formed by generally gradual color transitions.
Hodgdon et al U.S. Pat. No. 2,240,072 dated Apr. 29, 1941 and entitled "Translucent Laminated Article" and Borack U.S. Pat. No. 3,309,257 dated Mar. 14, 1967 and entitled "Color Changeable Embossable Laminate" disclosed additional prior art concepts for laminated tapes having color foil instead of a painted substrate while also being suitable for imprintation of similar indicia.
Other imprinting techniques have also been described in the prior art. However, it is believed that the references described above are generally representative of the prior art. Furthermore, techniques such as those described above have been used with tapes comprising a wide variety of plastic resins such as acrylics, allyl diglycol carbonate, cellulose acetate, polycarbonate, polyester, cellulose triacetate, polyestersulfone, polyethylene, polyethylene terephthalate, polyimide, polypropylene, polystyrene, polyvinyl alcohol, polyvinyl acetate, ethylenevinyl acetate, polyethylene oxide, polyvinyl chloride and a number of vinyl copolymers, for example.
Accordingly, there has been found to remain a need for a laminated tape and a method for forming and imprinting the tape in a simplified manner permitting greater versatility in both the design applied to the tape and color combinations possible in the finished tape as well. It is also thus apparent that simplicity both in the tape and the method for forming and imprinting it is also desirable.